THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[20:00:09] ANDERSON COOPER, CNN HOST: Good evening. Thanks for joining us on this Valentine's Day.

We begin our program with broken hearts in yet another American town, which today became the site of yet another deadly school shooting. A high school in Parkland, Florida, became the scene of chaos and panic just before the end of the school day. The Broward County sheriff says at least 17 people are dead, 17 people.

A suspect is alive, in custody. As is our policy on this program, we will not say his name or show you his picture. We'll update you on the investigation certainly and as information comes in over the next two hours. But as always and it happens too often, we'll keep our focus on the victims, their loved ones and the survivors -- high school kids, teachers, parents, brothers and sisters, people whose lives were lost or forever changed this afternoon, people who tonight have joined a terrible and a senseless club when that grows by the week in this country.

Right now, we're going to show you a short video taken inside a classroom during the shooting, difficult to watch. It is difficult to listen to. We blurred the faces of the students.

(VIDEO CLIP PLAYS)

COOPER: Randi Kaye joins us now from Parkland, Florida.

Randi, talk to me about the latest that we know about what happened.

RANDI KAYE, CNN CORRESPONDENT: Anderson, I can tell you that for sure, it was an afternoon filled with terror for so many. Any other day this affluent community outside Fort Lauderdale would be considered one of the safest in the state of Florida but today as you know, a shooter changed all of that.

A sheriff late this evening here told us that the shooting began outside the building and then entered inside the high school building. That is what we're told, that the shooter actually followed the students inside.

And tonight, Anderson, investigators have the gruesome task of going through that high school building and identifying the victims.

(BEGIN VIDEOTAPE) KAYE (voice-over): Around 2:30 p.m., the Broward County sheriff's office responds to reports of a shooting with multiple injuries at Marjory Stoneman Douglas High School. The student population close to 3,000.

At first, those inside the school didn't realize what was happening.

UNIDENTIFIED FEMALE: Kids were freaking out. Some kids froze. Some kids are on their phones. A lot of were on their phones just trying to Snapchat everything because they thought it was a joke and it wasn't. 2 KAYE: At this point, the shooters whereabouts are unknown. SWAT teams go from room to room, securing areas before allowing students and teachers to evacuate.

UNIDENTIFIED MALE: It's insane. It's unnecessary. It's out -- there's no words to describe how I feel right now. I was shaking. I was -- I was panicking, all out panic about the school.

KAYE: Students run to safety after they are escorted out of the school building, some with hands still in the air, others clutching each other for support.

Outside the school, first responders tend to the wounded, and parents anxiously wait to see their children outside of the lockdown zone.

UNIDENTIFIED FEMALE: Do you know -- is your daughter safe?

LISSETTE ROSENBLET, DAUGHTER EVACUATED FROM HIGH SCHOOL: Absolutely. Thank God, just 10 minutes ago, she was able to call me. I hadn't heard from her since 2:48. She kept texting me and she said that she was hiding, that she was fine, but for me to please call 911 because there was somebody hurt on the third floor in the 1200 building.

She was -- she was very nervous. She said that she could hear the person who was shot you know crying out for help and just was, you know, a nervous wreck.

KAYE: The FBI and ATF joined local law enforcement on-site. Police say they know the identity of the suspect and confirm he has left the school grounds. Just before 4:00 p.m., the Broward County sheriff's office announces they found the shooter and arrested him without incident.

(END VIDEOTAPE)

COOPER: Randi, I understand you've been speaking to families who were there as well.

KAYE: Anderson, as you know all too well, days like these are certainly heartbreaking. Here on the scene, when I arrived this afternoon, not long after the shooting, there were parents still waiting outside waiting and wondering if their children had survived. One of the first people I met was a woman who told me that she was still waiting for a word of her daughter, at least to see her daughter.

She'd gotten a text message from her earlier. She was had locked herself in a closet and had texted her mother saying, I love you, mom, if I don't make it, I love you, mom.

So, Anderson that's just you know one of the many feelings from families and parents here on this heartbreaking day, just a snapshot of what they've gone through.

COOPER: We should also point out, our Shimon Prokupecz reported just a few moments ago, new information apparently the shooter not only losing custody, is actually looking to investigators. One of the things that they have learned according to the reporting of Shimon Prokupecz, based on sources is that the shooter arrived at the school with a gas mask and some sort of smoke grenades.

And the shooter is actually the one who pulled the fire alarm, supposedly the idea being to get students to come out and have this be as big mass-casualty incident as possible.

Randi, thanks for that.

A short time ago, I spoke with Melissa Falkowsji who's a teacher at the high school.

(BEGIN VIDEOTAPE)

COOPER: Melissa, first of all, I'm so glad you were safe. How are you holding up right now?

MELISSA FALKOWSJI, TEACHER AT HIGH SCHOOL: I'm not really sure. It just doesn't seem like -- what happened today just doesn't seem real. I'm not really sure how to process it, like the emotions when today have been so extreme from just being you know totally terrified and trying to keep the -- you know, keep the students calm and then trying to make sure they reunite with their families and then trying to get myself home and then like finally making it home and then kind of sort of losing it.

I'm not -- I'm not really sure yeah like where you go from here and how you -- you know, how you deal with it.

COOPER: If you can -- if it's not too painful, can you just explain what you saw and heard? I mean, you were teaching this afternoon the fire alarm went off around 2:30 I understand.

FALKOWSJI: Right. So, it was fourth period and that's my newspaper class. So, you know, working with the kids who are making the school newspaper and the fire alarm went off and we had one this morning. But there have been times in the past where the fire alarm wasn't working properly, so we've had to you know kind of evacuate a couple of times -- so, we just you know followed the protocol you know which is we're supposed to when the fire alarm goes off, we have to you know evacuate.

(CROSSTALK) COOPER: You'd had a fire alarm drill this morning.

FALKOWSJI: This morning at 9:00, the fire alarm went off this morning. And so, we did our drill. And so, it is sort of unusual for a second one to go off in the same day.

COOPER: Right, and we now understand it was the shooter who actually according to the latest reporting, it was the shooter who pulled the fire alarm.

FALKOWSJI: Right, right. So, I mean, that's what we suspected, you know, as the situation sort of unfolded. So, you know, we make it out, you know, of my room and out of the hallway and we're starting to go down the stairs and the security guard who's posted in our area said, no, it's a code red. You know, go back, and so, you know, the teachers who were there called out to the kids and we started going back to the classroom and, you know, taking in kids and yelling to kids in the hallway to get inside.

And then after about 60 to 90 seconds --

COOPER: I'm sorry, code red did that mean this active shooter?

FALKOWSJI: It's an active shooter, yes. So, after about --

COOPER: And you had drilled for that?

FALKOWSJI: We had drill for this, yes. We had a training recently. We like we could not have been more prepared for the situation, which is what makes it so frustrating because we have trained for this. We've trained the kids for what to do.

And so the frustration is that we did everything that we were supposed to do, Bauer County Schools has prepared us for this situation and still, you know, to have so many casualties, you know, it's very -- at least for me, it's very emotional because I feel today like our you know our government, our country has failed us and failed our kids and didn't keep us safe. So --

COOPER: You heard code red, you got your students back into your classroom?

FALKOWSJI: Yes, so I turned around because we were very close to my room and turned around, open my door, pulled in my kids who some of them ended up in another classroom because they were too far away to make it back to me. I pulled in a couple of kids who weren't mine, they didn't know where to go and their classroom was across the school, pulled those kids in and then stood in the hallway for, you know, 60 to 90 seconds.

I would say, you know, calling two kids in the hallway to get into a classroom, to get into the nearest available classroom, didn't matter who their teacher was, where they were just to get inside. And then after about you know seconds, and I closed my door and me sort of huddled, you know, in the corner for a few minutes and then we, you know, I made the decision to move everyone to the closet. COOPER: Were you hearing anything at this point? I assumed the alarm was still going off. Was -- did you hear any shots? Do you hear anybody yelling instructions anywhere?

FALKOWSJI: No, I work on the opposite side of the school as where the shooting occurred. I used to work in that building but have since moved. So, we were on the opposite side, but within you know two to three minutes, I would say we heard helicopters and sirens and -- but we didn't hear -- we didn't hear any shooting.

COOPER: How -- so you said you put kids in the closet? How many kids can you fit in a closet?

FALKOWSJI: Today, I fit 19 kids in the closet, plus myself. So, I mean, we managed to all get in there and we just sort of huddled in there for about minutes. It was hot. It was hot.

COOPER: And does everybody try to stay quiet?

FALKOWSJI: Yes, everybody, you know, is on their phones and trying to get in touch with their family and, you know, we're staying quiet and, you know, I have had some girls who were crying and just trying to, you know, keep them calm and tell them that they're OK and that they're going to be OK and everything's going to be OK and then you know trying to hold yourself together, you know, like in that situation. You're trying to hold them together and, you know, my family is calling me to see if I'm OK.

And, you know, so you just kind of do the best you can and sort of, you know, muddle through but, you know, try to do the best you can for, you know, the kids that you're supposed to keep safe.

COOPER: And I understand it was a SWAT team that actually came to get you out.

FALKOWSJI: Yes, the SWAT team did come and get us out. So, we heard them in the room and they called out to see if anyone else was in the room because we were hiding in the closet. And so, then we kind of sort of slowly opened the closet door and said that we were there and then they had this come out, you know, single file and they went through the rest of the building, you know, checking it, because I guess at that point, you know, all the text -- the text and the messages we were getting was telling us that, you know, and the news reports was that they were still looking for the shooter. And so, they were you know going through the building and sort of clearing it.

COOPER: Do -- I mean, are all the kids that you know accounted for?

FALKOWSJI: I mean, all the students that I teach are accounted for. You know, I have heard rumors about other students that you know aren't my students but, you know, are related to students that I have and I, you know, don't know if that knew those reports are true or not. And so, it's hard for me to say -- I mean, until the names come out and we'll know if any of them are my current students or former students or I know I have heard that some of my colleagues may have been killed, and I won't know until come out, you know, who they are. COOPER: Melissa, I'm so glad you're safe and you were able to protect your students. The kids are lucky to have you as their teacher. Thank you for talking to us into this impossible situation. Thank you.

FALKOWSJI: Thank you.

(END VIDEOTAPE)

COOPER: Well, let's get all the latest now. James Gagliano is joining us. Philip Mudd, Cedric Alexander and Juliette Kayyem.

Jim, I mean, you used to lead an FBI SWAT team. Just in terms of what you what we know so far, what stands out to you?

JAMES GAGLIANO, RETIRED FBI SUPERVISORY SPECIAL AGENT: This takes me back to April of 1999 and I was a member of the FBI's hostage rescue team at the time, Anderson. One of the biggest thing that law enforcement does after an incident like this is they conduct an exhaustive after-action review and it's kind of like a best practices sharing and some of the lessons learned after Columbine, we called it post-Columbine, were stark and important and I believe saved a number of lives.

COOPER: Columbine changed everything in terms of police response.

GAGLIANO: It changed everything. Prior to Columbine, nobody understood what the term active shooter meant.

COOPER: Prior to columbine and at Columbine, police set up a perimeter to secure while this was still going on. They didn't move in immediately.

GAGLIANO: Tactical teams had to be homogeneous. They could not be heterogeneous. You couldn't take a piece from a local police department, put them with a state police officer and a federal agent. You couldn't do that.

Nowadays, what we do is go to the sound of the guns. You get one, two, three, four people together, we're trained, we use particular formations different things that we say --

COOPER: You don't make for a SWAT team necessarily. It's the initial officers who are on the scene. If they're -- if it's a bike cop, it's a traffic cop, whoever it is, you go in try to get the shooter.

GAGLIANO: You're putting a heterogeneous group together. You're going to the sound of the guns. The number one goal is to interdict the shooter or shooters.

In the old days, it was you took land. You went in, you clear the room, then you slowly and methodically move to clear the next room. In this instance, we learned again post-Columbine get to the shooter as quickly as possible and that's what they clearly did here.

COOPER: And the reason of that my understanding is the FBI has done exhaustive reviews of every active shooter situation over the since Columbine I guess and have learned that most of fatalities take place in the first six minutes these things are very short usually in duration and if you're waiting to set up a perimeter and waiting to go room from room, the deaths are all going to be done by the time you actually find that person.

GAGLIANO: We go back further than 1999. We go back to August 1st of 1966 in the University of Texas clock tower shooting. And in that instance, it was the same thing. Most of the shootings happen right way, two heterogeneous folks, there was a campus police officer and a local deputy went up and confronted the gunman, and that was really the birth of Special Weapons and Tactics Teams.

COOPER: Phil, it's interesting because I've been in schools and watched their active shooter training drills that they have and a lot of it is, you know, the teachers bring the students into the classroom. They locked the doors. They pulled down a blind over the door. They huddle in a closet or in a corner as we heard teachers say.

The interesting thing about this shooter pulling the fire alarm, clearly that was meant to -- I mean, not only to get people out and group together and maybe kill as many people as possible, but it also as a way to overcome the active shooter training if everybody's supposed to just hide in the classroom if, all the sudden, they hear a fire alarm they're going to be tempted to go out.

[20:l5:02] PHIL MUDD, CNN COUNTERTERRORISM ANALYST: No, that's right. Anderson, let me pick up on what James said, somebody I've known for a long time. James is right.

You look at this and one of the first questions you have is not only what happened in this particular instance, but how do you put it in context and sort of try to find lessons learned. So, can you get inside somebody's head to determine who's going to conduct an act like this? When, if you can't do that, can you determine how to secure the perimeter of tens of thousands of grade schools and high schools across America to prevent this from happening?

If you can't secure that perimeter, what happens when someone breaches the perimeter and gets inside and starts shooting? What's your incident response? And then you have somebody who says, I'm going to break down your incident response by pulling the fire alarm and forcing people to come out.

I think one of the difficult questions we'll see in the next day or two is if a young teenager decides he wants to kill a lot of people and acquires a weapon that was legally acquired and gets into a high school, how are you going to prevent him from accessing tens or hundreds of students? What's the preventive measure? People are going to want answers.

And, Anderson, I'm not -- I'm not sure the answer is that we'll find any answers. I don't think so.

COOPER: You know, actually, the FBI and Broward County are now asking people who have video and you heard one of the teachers talking about Snapchat and we saw it -- we showed one video. They're asking -- they're saying -- they tweeted out this saying, the FBI set up a Website where you can upload images and video of the Stoneman shooting. Visit FBI.gov/parkland shooting to submit any information you have on the shooting that occurred at Marjory Stoneman Douglas High School.

Interesting way, I don't think we've seen that before or immediately they're putting out an appeal for any students or teachers who were taking Snapchat videos or any kind of Instagram videos to send it to police so they can try to piece together, Phil, a video documentation of what went on.

MUDD: Well, that's not that's not the only reason, Anderson. The first question I think we're already almost to the end of resolving this is when you see that video, do you see anything that suggests he came in with another accomplice? My first question here is not the tragedy of 17 or more people who were killed, but let's ensure there wasn't anything else going on, coordination with another student that suggests there's a follow-on incident.

Then you have the question of evidence. If this person goes to trial, do you have evidence as you suggest, you know, sort of iPhone video for example that will help. Lessons learned, do you have video that suggests to us ways that we could have handled this better?

I think the bigger question, Anderson, what you're getting on is in the age of digital media crowdsourcing crime is getting bigger and bigger and bigger. Everything from ATM video to videos from a iPhone at a high school is going to become critical not only in determining who did it but in determining did something happen that we could prevent in the future. It's huge.

COOPER: Cedric, it is chilling to think that, you know, we talk about terrorists as being kind of a learning enemy that they adapt their tactics. The idea that a -- you know, a kid an 18-year-old or 19- year-old could look at other school shootings, maybe he even had gone through active shooter training as a student in that school and then try to figure out a way to how to overcome and get more students out of the classroom when they're supposed to be huddled inside.

CEDRIC ALEXANDER, CNN LAW ENFORCEMENT ANALYST: You're absolutely right, Anderson, and all you need is an imagination. And if you take an 18-year-old kid such as this suspect we have in custody now, that's in custody now there in Broward County, he probably has been through that training, probably ever since elementary school. He's only 18 years old. And in fact, he wasn't even born when Columbine happened.

So, let's take into account a number of things. We can talk about what happens when the alarm goes off and police respond, and they do a terrific job. But unfortunately, when that alarm goes off, a body count is already being added up. And in this particular case, 17 young lives were lost today.

Police got there rapidly. They did a great job. The teachers did a great job. Everybody did the best that they could do under the circumstances.

So we can go back and we can analyze what occurred, but the important piece in all this and it, Anderson, and I think your guests just before me mention, is the whole prevention piece. We got to go back and we got a look at how do we protect our Second Amendment right but at the same time as you heard the teachers say that you were interviewing moments ago in the last segment that she don't feel the government protected her.

So, we got to do some things in this country that's legislatively is going to give us an opportunity to prevent these types of events because once someone penetrates into that building and it doesn't take much quite frankly, no matter how much you secure it, someone competing it piggyback, someone can break a window and get in, it's a variety of different ways. We got to get into the prevention piece of this, and that mean our Congress and our White House in our nation, our states, are going to have to do a better job of trying to protect the people, so that we don't continue to have this conversation month after month and year after year.

[20:20:11] COOPER: Juliette Kayyem, though, if you have a large school with multiple entrances and multiple exits and most of these fatalities according the FBI take place in the first couple of minutes and the first six minutes or so, that's when most of the killings take place, if you have a an AR-15 or anything that can fire off a lot of rounds, no matter how quickly police get there, or even whatever police security guards are already on scene, you know, as school security guards, if you have a large facility and you have a large, you know, capacity magazine, there's not much you can do to stop that.

JULIETTE KAYYEM, CNN NATIONAL SECURITY ANALYST: That's exactly right and so, we can talk about training and fortifying schools. That's great. But we begin -- we have to also talk of course about the weapons.

And to think about our responses in light of the weapons that are out there, in other words, the Columbine lesson was, you know, run hide and only engage if you must, right? That's always -- that's what we're training. Just the way these gun these weapons are able to kill so many people so quickly, we are going to have to start thinking about whether engagement actually will protect more lives in the long run. I don't know the answer to that but, you know, these are not handguns anymore. These are not things that you know have six or seven bullets and then they go out, so that's the first part, is to rethink our planning.

And then the second is I refuse to believe and you can call me delusional or maybe I'm just a mother, I refuse to believe that there aren't moments in Nikolas Cruz's last three or four months where people aren't beginning to recognize something very bad is about to happen. How does someone like this get the kind of money to buy weapons like that? Who's paying for his car? How does he get all the materials for today? Who is he talking to, his social media posts?

So, you know, all of that seems so obvious to us now, but it was obvious to other people before and that's where we have to begin to empower people to say something is terribly wrong and we can't just -- you know, anyway, we then take responsibility for the people around us.

COOPER: We're getting more and more details and we will be throughout these next two hours. Obviously, we're going to bring them to you throughout the evening.

Right now, let's get the latest on the investigation. CNN's Shimon Prokupecz joins us with that.

So, you've learned a lot just over the last hour so. Just bring us up to speed.

SHIMON PROKUPECZ, CNN JUSTICE REPORTER: Yes, certainly, Anderson. A lot of new details coming in the last hour, and we're told that the suspect and this is important here, is talking with investigators. It appears that he's providing information and we're getting some sense of what they've learned. And this here is what some of what they're now learning, that the shooter here pulled the fire alarm to draw people out. He wanted to get a higher death toll.

It appears this is based on some conversations perhaps that they had with him, indicating there's been some level of planning, the officials say. We're also told that he escaped from the school by blending in with some of the students, as they were leaving, as they were perhaps out of the building. So, he tried to blend in with some of those students and was briefly able to escape.

This is what these law enforcement officials are telling us and we're also learning and as, you know, from the sheriff when he held his press conference, they're really learning a lot from his social media postings. You know, the sheriff here, calling it disturbing. He would not specify why it was disturbing, but certainly, he raised some issues on social media, kind of wondering why no one had seen these posting.

And then we have the gun. The gun we're learning is this AR-15 style rifle. The sheriff talked about it and how they were that multiple magazines and now, what we've learned is that if the ATF is tracing that weapon in hopes of trying to find out, you know, did he buy this weapon on his own, did someone buy for him, kind of to learn the history of this weapon trying to answer some questions, you know, here about where he got this gun.

COOPER: And I think I heard you report earlier about an hour or so ago that he had actually arrived and when he pulled the thing, he actually had a gas mask. Is that correct?

PROKUPECZ: Well, that's coming from Senator Nelson here, the Florida senator. He is saying that he was wearing a gas mask. There were some smoke bombs as well. He's been on our air today. He said it several times.

We've not been able to confirm that with law enforcement.

COOPER: OK. PROKUPECZ: But again, you know, we have no reason to believe he's -- he doesn't know he's talking about. But again, just goes to the level of planning. You know, there are indications from law enforcement that this was a well-planned.

COOPER: How well-known was this former student who's 19 years old known to other students? How well-known was he?

PROKUPECZ: So, law enforcement has to talk to his both students who knew him very well and then there are some students who say that they've never seen him. You know, keep in mind that he was expelled from the school a year ago. Also students who talked to reporters outside the school, they say they knew him.

[20:25:00] The key here is that they're saying that he liked guns. There was this -- everyone knew who he was. This one particular student was telling a local reporter that he liked guns and that even more important here is that they were not surprised to learn who was behind this when police announce who the shooter was, they suspected it was him.

You know, it's just not -- it's not clear why they thought that. But this is one of these situation and appear based on what some of the students are saying and perhaps what law enforcement is learning, the question is going to be, there were signs here and just why -- just why no one came forward to report any of it.

COOPER: And the FBI is working with local authorities on the investigation, right?

PROKUPECZ: Yes, they are. And so, in this capacity, look, right now, there's nothing to indicate that this shooter is going to face federal charges. This will probably be handled on the local level, but the FBI as they do in a lot of these cases as well as the ATF, they come in to assist, they come in to help process the crime scene. Some of the video that you know they're asking for process some of the video, process the crime scene, helped question witnesses.

And then the other key thing here, Anderson, is the families. They come in and try to help some of the families who we obviously can't forget about and sort of what they're going through and the FBI today also put out a tip line asking people if they have any information to call them, because you know they want to know what else was missed here.

Were there signs here that were missed? And what they will do as part of that is probably build out a timeline, go back in time, you know, perhaps a year, maybe longer, and see exactly what was missed and what was going on in this guy's life, certainly in the last year.

COOPER: All right. Shimon Prokupecz, appreciate that. We'll check in with you again.

Seventeen people were killed, most of them were found inside the school, but three people were found outside, about a dozen others are wounded, hospitalized at this hour. Every second is obviously critical in a tragedy like this. Police and EMS trained for it. They hope they never have to use the training, but today's -- they certainly did in Parkland, Florida.

I want to listen to those first responders as they work quickly to help the victims.

(BEGIN AUDIO CLIP)

UNIDENTIFIED MALE: Seventeen Julia five, I have the gunshot victim. He is by the entrance, on the west side of the school.

UNIDENTIFIED FEMALE: Fire rescue is being notified.

UNIDENTIFIED MALE: Does you know where the shooter is?

UNIDENTIFIED MALE: We don't know. But we are heading into the building. The 13 building.

UNIDENTIFIED MALE: Does anybody have bolt cutters? I can get this kid out of the fence. He is stuck in the fence. I need bolt cutters.

UNIDENTIFIED MALE: The coach is with him. He's helping over the gate.

(END AUDIO CLIP)

COOPER: Let's get an update on the people who were injured right now.

CNN's Kyung Lah joins us from one of the hospitals.

So, what do we know about the status of some of those injured tonight?

KYUNG LAH, CNN NATIONAL CORRESPONDENT: Well, it was a total of 17 patients that were taken from this school shooting to various hospitals. There are two main hospitals that these patients were taken to.

I'm standing, Anderson, at the closest hospital to the school. Eight patients were brought here. These were eight patients. We don't know their ages, that they were all students or teachers but they were brought here. Three in critical condition, three still in surgery this evening.

We are told by the hospital that they are in stable condition. Two patients did not make it out of this hospital. They died here at this hospital. And in an unusual turn, in part because of the close proximity of this hospital to the school, one of the patients brought here and we're not including him in the eight is the suspect. The suspect did arrive here and was treated, Anderson.

COOPER: The -- can you described the scene there outside the hospital right now because -- obviously, I mean, it's got to be or at least throughout the day, it must have had been chaotic?

LAH: It's -- it really reminds you that what we're dealing with here is families. When we arrived here, there were -- there's some chaos. There's some control chaos here at an emergency center, but where we are is where the hospital asked us to park. We're a bit of a distance away from the emergency room doors. You can see it in some distance behind my right shoulder.

The people who are in the parking lot closest to the emergency room, you could almost experience the horror with them. They were pulling up in minivans, in SUVs, these are the vehicles of families, mothers and fathers running out of these vehicles heading to the emergency rooms.

You could clearly see them talking to the police outside the door then being directed to another part of the hospital. There is so much fear and chaos on parents who just simply can't get enough information, maybe they don't believe the information they start checking the hospitals on their own, and that's really what we saw unfold, panic, concern, trying to find the answers and some of them just being whisked away to certain parts of the hospital.

It is a reminder, Anderson, that what we are dealing with are children, child victims and parents who are seeking answers -- Anderson.

COOPER: Yes, that impossible wait that we've heard about from so many past shooting for parents often have to wait for hours, hours until they find out the fate of their child.

We do want to share you that we've mentioned this a short time ago that the Broward County Sheriff's Department had tweeted out requests from the FBI to send in videos to a site that the FBI that setup, fbi.gov/parklandshooting to submit any information that people have on the shooting, any Snapchat videos, any Instagram videos, anything that they shot on their phones.

We want to show you a short video that was taken inside the classroom during the shooting, it really just give you a sense to just the terror of the situation, better than words could, it's tough to watch, tough to hear, we have blurred out the faces of the students.

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: Holy --

UNIDENTIFIED MALE: Oh my god! Oh my god!

(END VIDEO CLIP)

COOPER: Just one classroom. Again, we'll not say the shooting suspect's name. We'll not show anything photos of him, we don't want to give him more publicity that he probably would desperate to have. But investigators are learning more about him and we do want to give you as much information about him as we can. He's a former student at the school. The Sheriff said he was expelled for disciplinary reasons. Our Senior Investigator Correspondent Drew Griffin joins us now with more. So what do we know about this person?

DREW GRIFFIN, CNN SENIOR INVESTIGATIVE CORRESPONDENT: You know, Anderson, as we have waited for absolute confirmation that the suspect matches his online profile, we've been gathering that information. It paints a very dark picture. The Sheriff alluded to that. What we have been finding is this posting some of the comments posted under the same name as the suspects written under videos posted on YouTube and other sites. And I want to show them but I'll bring you them, nine months ago it was this, "I am going to kill law enforcement one day, they go after good people."

Six months ago, "I'm going to watch them shit fall. I wish to kill as many as I can." And from just months ago, this is October 19th of last year, there was this comment attached to an internet video, Anderson, "I want to shoot people with my AR-15."

CNN talked with the former fellow student who told this, I can tell you this is a violent kid, he wasn't in my class but I saw him in class, he said. He was one of those kids that if you did wrong, he would get you back. He would threaten to kill people. He wore dark clothes, put weird marks on his arm, he was pretty shy. The student told us that the suspect have left his high school last year, the year before he couldn't remember, but that was confirmed by the Sheriff tonight who says the suspect had been expelled for disciplinary reasons.

There's also -- it's a posting by the person we think is this suspect, Anderson, if they are all him, what happened today was completely telegraphed by the shooter himself.

COOPER: Yes. I mean, do we know anything about this person's family? Where there parents and, I mean, could you want -- obviously, the question is, didn't anybody who was close to him, any family member, weren't they aware these postings? I mean --

GRIFFIN: We are unclear of his family situation and that may have been a big problem in his life from what we gather and we just don't have that nail down. We're trying to determine if, in fact, he did have parents at the time of the shooting. So we are looking into that, Anderson, trying to track it down, it's all in flux but again, these postings as alluded to by the Sheriff and his news conference show a very, very dark individual forecasting exactly what happened today.

COOPER: Yes. And specifically with the weapons saying what do you want to do with that weapon. Drew, thank you.

The Congressman for the district where the shooting took place, Rep. Ted Deutch, I just spoke with him by phone just a short time ago.

(BEGIN VIDEOTAPE)

COOPER: Congressman, first of all, I'm so sorry for what your community is going through tonight. What's the latest that you are hearing from law enforcement?

REP. TED DEUTCH, (D) FLORIDA (via phone): Well so, the latest from law enforcement is that the number of fatalities is now up to 17. They're learning more information about the shooter, about the kind of weapon that he used. And that's the update on the numbers, Anderson, but the difficulty is that these 17 fatalities have family members and the community is really going to struggle in the coming days and weeks. Just a horrific terrible, terrible situation.

COOPER: The amount of preparation which went into this, Senator Nielsen were just on the phone and our own reporter were just learning from law enforcement that apparently the shooter is not cooperating. He actually came in a gas mask with smoke grenades to the school and was the person who set off the fire alarm, the idea being drawing students out and creating as many casualties as possible.

[20:34:58] DEUTCH: Right. Like this is -- the details of what happened today are important and that investigation will continue. We need to know much more about who this person is and to try to understand everything surrounding the shooting. But ultimately, this is the worst day for Douglas High School for that wonderful community of Parkland because, at this point, I believe, 17 lives.

COOPER: Yes.

DEUTCH: And look, this is -- this is one of the finest schools in the state. I was there just a couple of weeks ago talking to these kids about what they can do to be involved in these communities and every one of these kids and their families now need into community to be with them, to help console and to help stand up and to help them overcome the horrific activities of today.

COOPER: Will something change because of this? I mean, as you know, time and time again, people in, whether it's Aurora, Colorado, or after Columbine or Sandy Hook, I mean, have said, you know, something now clearly must change, do you think it will?

DEUTCH: Anderson, I learned something about heartwarming and frankly a little obscene today, which is the colleague of mine who stop me on the floor offered condolences and then handed me the protocol of the way to deal with a mass shooting like this because these had truly the district under have been so many. Does this mean that there's going to be an immediate rush to do something?

You know, history would say no. But it doesn't matter -- it doesn't matter what's the meaning (INAUDIBLE), these kids that went to school today who never went home to their families, they were hard have been -- they were shot because of how they feel about the Second Amendment or who they voted for president or how they feel about the NRA. That's not what this is about. This is about preventing mass shootings like the one that happened today and everybody wants to do that.

It doesn't matter we (INAUDIBLE), everyone wants to do that and so now we got it, you bet, we go to redouble our efforts and not to simply throw up our hands and say, nah, this is just what we got live with. We don't. Nobody should have to feel the way my community feels right now.

COOPER: And so those watching tonight, members of your community, people across the country, I'm just wondering what message you have for them?

DEUTCH: Well, I'm going to be honest with you, Anderson, I have said before when there's a mass shooting that often prayers are enough and I stand by that. That's the (INAUDIBLE) but, you know what, they really mean a lot and to all of the people in South Florida and around the country who have offered their support, it's incredibly appreciated. It's really important. This is a great community that's going to need to be with them, to help them over the coming days and weeks and I'm grateful for the outgoing support.

There will be time, we're going to have to double down our efforts to try to prevent this happening in the future but for right now, I'm just so grateful for the support that being offered and I just want people to know how much it is appreciated.

COOPER: Congressman, appreciate your talking to us tonight. I'm sorry the turn of these circumstances.

DEUTCH: Thanks, Anderson, I appreciate it.

(END VIDEOTAPE)

COOPER: Trying to talk to as many people who were there and experience and kind to see it from these many different angles as possible. Joining me now on the phone are Zaphena Jasmine, a student at the high school and her mom, Khadijah Jacobs.

Zaphena, first of all, I'm so glad you are OK and you're safe. How are you doing right now?

ZAPHENA JASMINE, SCHOOL SHOOTING SURVIVOR: Hello. I'm OK. For all of those who are lost during this, I want to say to the families, we stand with you and we're sorry because these administrators and students are humans too and they didn't deserve to go out like this.

COOPER: If you can, Zaphena, just tell me what you hear, what you saw, what happened today? I understand there was the fire drill that went off. We now believe it was the shooter himself who actually set off that fire drill, what happened then?

JASMINE: Well, I was in class, we heard the fire drill. I didn't really budge because they already had a fire drill that day. And there was this seemed no reason for second one and my teacher said this wasn't really scheduled. And so, then I hear on the announcement that to evacuate. So, we all get out. I'm going down the route and I'm halfway down the stairs from the route to those in 700 building and an administrator is blocking my way and saying go back, go back, it's a shutdown.

[20:40:12] And after he said that, I heard four, five gunshots and we all started booking it to a classroom that was open. So, that's the time most teachers already lock their doors and they're not opening it.

COOPER: Did you know there were gunshots right away? JASMINE: We heard a bunch of pop, pop, pop. If it wasn't real gunshot, it was a drill they were training us for. But either way I took it seriously.

COOPER: How long -- when you finally got into a classroom, how long were you in that classroom for?

JASMINE: I was in that classroom for two hours, because when it came to the evacuation process, they go class by class one at a time just to make sure. So, I'm sure there are students that are in there for a way longer.

COOPER: That must have been so scary?

JASMINES: Yes. But I kept calm because if you are freaking out, other people around you are going to freak out and that's never OK. You have to stay quiet during stuff like that.

And, yes, I am not going to lie, I was praying with my friend in the corner of the room just making sure everybody felt OK.

COOPER: And could you -- when did you know something terrible had happened?

KHADIJAN JACOBS, MOTHER OF SCHOOL SHOOTING SURVIVOR: She actually text me immediately. They told me the shooting was that started at 2:35 and I received a text at 2:36.

COOPER: Wow.

JACOBS: Yes. And so, I put on the news because I'm like, OK, let me see if it's for real. And it was all over the news. So, I just immediately stayed on the news. I immediately posted on social media so that way other people are made aware.

And she continually text me throughout the entire time. Because, of course, I want to make sure my daughter is safe.

COOPER: Sure.

JACOBS: So we were just texting constantly back and forth. So, she actually was keeping me calm. You know, she said, "Mom, everything is OK." She just text me back, I'm OK. You know, every so often. And there once I saw they apprehended the shooter, at Wyndham Lake. Now I know OK, it's safe now, so now they are taking their time going into each classroom to slowly get all of the students out.

COOPER: And, Zaphena, when were you able to finally able to finally reunite with your mom?

JASMINE: It took a couple of hours. Because I -- everything was blocked up as we wanted to make sure, because I was in lock room originally, but that's towards the direction of the school and they don't want anybody out there on their own. Just walking to place because the area still, somewhat dangerous. But I had to get a ride with a friend. And yes, I am here and I'm with my mom now. COOPER: What was that like it see your mom?

JASMINE: My mom has lost a lot this week and I know she would have been worried to think that she might have lost me too if I wasn't constantly talking to her. And you got to think about your family during this situation because that's all you have to hold on to sometimes.

COOPER: Yes. Especially in a time like this you really realize how important that is.

JACOBS: Yes. I lost my mother just last week too.

COOPER: Oh my gosh. I'm so sorry.

JACOBS: So to experience this, that's why, you know, for her to constantly keep in contact with me, it really helped. You know, but my heart goes out to those 17 that lost their lives. I'm glad my daughter is safe, but she lost friends. She lost possibly a teacher. We don't know yet. So we're just waiting. But our heart goes out to each and every one of those family members. And I'm just ready to do because, yes, I pray and I always tell people to pray, but I also tell people you need to move on those prayers as well. And so I'm just preparing whatever needs to be done, you know. I'm there for them.

COOPER: Yes. Well, Khadijah and Zaphena, I appreciate your time. And, again, I'm glad that you are both safe. I'm glad you are together tonight.

JACOBS: Thank you.

JASMINE: Thank you.

COOPER: Thank you. We're going to take a short break now. We're going to have more on the events in Florida when we continue. We'll be right back.

(COMMERCIAL BREAK)

[20:43:38] COOPER: I want to show you a text message that is indicative of a lot of the heart breaking text messages that were going back and forth in Parkland, Florida today.

A young woman texted her mom, "If I don't make it, I love you. And I appreciate everything you did for me."

Thankfully, that student made it out safe. Tragically, others did not. We know 17 people have died in Parkland, Florida today not long after the news broke.

Connecticut Senator Chris Murphy put the blame squarely on the institution where he works.

(BEGIN VIDEOTAPE)

SEN. CHRIS MURPHY, (D) CONNETICUT: Did this happens nowhere else other than the United States of America. This epidemic of mass slaughter. The scourge of school shooting after school shooting. It only happens here not because of coincidence, not because of bad luck, but it's a consequent of our inaction. We are responsible.

For a level of mass atrocity that happens in this country with zero parallel anywhere else. As a parent, it scares me to death that this body doesn't take seriously the safety of my children. And it seems like a lot of parents in South Florida are going to be asking that the same question later today.

(END VIDEOTAPE)

[20:50:03] COOPER: Senator Murphy's home state of course was the scene of the shooting where 26 victims were first graders, teachers and a principal in an elementary school in New Town. It's also reminisce another event even earlier Colorado's Columbine High School.

With me now is author Dave Collin, who wrote the book "Columbine" which if you have not read it, I urge to read it. I've read it two or three times. It's just an incredible read. It changed my whole perspective on this. Nothing ever changes. I mean we talked about this. You've been on countless times, and it just -- nothing ever changes.

DAVE CULLEN, AUTHOR "COLUMBINE": It doesn't. And that's what I can't -- I couldn't agree more with what he said. We don't do anything, and the gun thing is -- we've got to do something. But at least there I understand the politics of it. Some of the other things like screening for teen depression, that's easy. That's not political. It's really cheap. There's a one page form. I did it to my doctor's office, it takes 30 seconds. It's highly effective. Why don't we start there?

COOPER: And you said studies show a lot of these shooters have depression.

CULLEN: Exactly. Exactly. That's the greatest number of them. So the definitive report the secret service did where they studied all the school shooters for more than a 25-year period, and 78% had either suicidal attempts or had talked about attempting suicide. So that's an astounding number. And this is in a situation where looking for profiles, they weren't all loners, they weren't outcasts. They weren't all white. They were black and they were all over the map from almost every single situation except almost all being male. Nearly all of them had some kind of sense or failure or loss and depression. Those were the only common factors.

COOPER: How much is the desire for publicity or infamy part of this? I mean I'm wondering, since we don't name them because I think that that is part of it. But when you, you know, looked at the Columbine shooters and that was an unusual one that you had two working together. I mean, they wanted that to be a mass casualty incident, even bigger. And they wanted it to be you had explosive devices.

CULLEN: Exactly. That's runs throughout of this -- runs throughout almost all of these. But I think we get a little trouble when we call it, you know, fame or even infamy because people have difficulty understanding that or believing OK, are they really out for that. When you really look at the profile of these people and they're desperate, they're people who feel unheard, who feel like failures. They feel small and insignificant. They're looking for some sort of success, for the world to hear them. So it's this kind of lashing out and feeling powerful and being heard and feeling like they're making an impact. So that's not exactly fame.

COOPER: Right.

CULLEN: But that's what we're talking about, someone who feels like they really did something and who feels powerless in this moment. It's a moment of awe and power, and then we in the media provide the coverage. They're not really powerful unless they're actually heard and have that impact.

COOPER: They -- also, I mean, in your research, how much is known by other people in their orbit, their family members or friends? I mean, this guy, some of the social media posts that Shimon Prokupecz has already seen, you know, are laying out, you know, I've got an AR-15 and I really want to kill people.

CULLEN: That's kind of astounding that still happens. After Columbine, the same secret service report found an astonishing number, I believe in the 70% or 80% had told people they were going to do it. Several people had told multiple people. I was under the impression, I mean, nobody has studied as closely since then, but that that number was dropping because it used to be kids always assumed that was a joke, right, because nobody did this, so when somebody said that.

But after Columbine and after, you know, Virginia Tech and New Town and all these, the perception was more of these kids who did hear those things thought it might be realistic.

COOPER: All right.

CULLEN: And did report it. It's really kind of astonishing to be hearing now that it was right out there on social media and nobody was turning them in, because we have a huge number of foiled plots. A lot of those we don't hear about, but there's more plots that are foiled or whatever you want to call it, where authorities close in and arrest them before it happens than do happen. Why that didn't happen here, I don't know. Nobody sort of came forward.

COOPER: The other commonality in the aftermath of all these, of course, is those who say, well, if this is not the time to talk about any kind of gun legislation or gun control -- I mean we hear that time after time, and then the moment passes, and of course nothing then is ever talked about.

CULLEN: Right. I mean, excuse me for rolling my eyes there. I mean, that is the most cynical tactic and so obvious, and it also falls apart where there are YouTube videos now of famous victims and survivors of many of these people. I think Connie Sanders, you might have had on, who is Dave Sanders daughter from Columbine.

COOPER: Dave Sanders who pled out in Columbine.

CULLEN: Exactly, who is a heroic teacher --

COOPER: Right.

CULLEN: -- who died saving so many kids. His daughter, people have Virginia Tech, a whole lot of high-profile survivors have, you know, made videos saying, yes, we want this talked about immediately after. We are the victims, and we're not buying your argument. Of course we want this.

[20:55:12] You know, we have fire drills in America right now, because of a disaster, I believe it was in the 1950s and I think it was in a girls high school, forgive if I am -- but there was a disaster, a lot of people got killed, so we had to do something. We started fire drills. Now we take that for granted. Most of the kinds of things we do now are because of reaction to something that happened.

COOPER: Now at this.

CULLEN: It's putting our head in the sand, so you actually said like, oh, we can't do anything because that would be, "politicizing it." No, that's being sensible.

COOPER: Yes. The column -- the book again is "Columbine." I urge people to read it. Thanks very much.

CULLEN: Thanks.

COOPER: Appreciate it. Back now with our panel. I mean, James, the fact that the shooter was known to the school, that he'd already been expelled, and yet he was still able to get inside, take all these lives, we don't yet know how he was able to get this AR-15.

JAMES GAGLIANO, CNN LAW ENFORCEMENT ANALYST: Sure. I mean again, kind of what you guys were just speaking about, we've got to look at this on the continuum. You want civil liberties in this country, or you want to be safe. We want a little bit of both. And unfortunately the only way to make sure that we keep people safe is a police state. We've got over 300 million weapons in this country. We have about 1 million sworn law enforcement officers, Anderson and if they work 365 days a year and work three shifts a day for 24 hours seven days a week, we can't possibly be there on-scene to protect everybody.

Think about it from this perspective. The shooter was expelled from school. Schools are gun-free zones, but the shooter elected to come back to that school. We know there was a school resource officer there, but one resource officer for 3,000 students in a fairly large area. It's the same thing as an order of protection. You can go to the police department and get an order of protection, require somebody who's harassing you to stay at least 100 yards away from you, 300 feet. But if that person shows up and doesn't want to honor that, how do you stop it unless you put a uniformed cop or FBI agent in every single person or armed.

COOPER: Or armed teachers with some people -- GAGLIANO: Or armed teachers, that some have made a strong case for

because it's just difficult. What bad guys do, what evil people do, and what in this instance the mentally unstable that fall into that evil category do is take the path of least resistance just like water. So if they show up at a place and we want our school zones to not look like a prison compound, that's where they're going to go.

COOPER: I believe we should point out. We are expecting some comments being made on press conference from law enforcement some time just in the next few minutes. We're obviously going to bring that to you live. Very close to the top of the hour already.

Phil, how significant is it that, first of all, the shooter did not take his own life, was not killed by law enforcement, and seems to be talking to authorities?

PHILIP MUDD, CNN COUTERTERRORISM ANALYST: That is significant to me. You look at a couple of issues and I'll add one to that. The fact that he shot a bunch of people -- and I'm going to presume some of those people are 2individuals he didn't know. He clearly, took in my mind, didn't intend to die in the incident. My first reaction to that as a former counter terrorism guy, is this someone who had a Jihadist, a suicidal tendency?

Looking at what he did, going in, surviving the incident, shooting this many people at a high school he attended, when he posted those kinds of things on social media, my initial reaction is he had some kind of grievance that does not relate to the world I used to live in, a counter terrorism world. It's a grievance that his family will know about, his parents will know about, his friends on social media will know about.

And to pick up on James's point, it's a grievance that you're going to look at and say, there's 330 million Americans, how do you prevent somebody like that from a grievance that might affect a million kids from entering in a school zone? I don't think you can do it, Anderson.

COOPER: Julia, our reporting the weapon that were talking about was an AR-15 rifle. Is there any reason in your view for those weapons to be available to civilians obviously sort of incredibly, you know, popular weapon?

JULIETTE KAYYEM, CNN NATIONAL SECURITY ANALYST: Yes. No. It's not just me. I mean, its international association of chiefs of police. It's most people who are actually in law enforcement and think about ways to protect their communities. I don't know personally everyone on your panel. I would suspect that our political beliefs are arranged of your four national security or law enforcement guests. And I think all of us are actually on the same page about the gun issue.

So I now think that it's political not to talk about it and to not discuss ways in which we can minimize the risk to our communities when you get sort of broad bipartisan support to get a little bit smarter. No one's pretending that a law is going to solve everything. But our job is to minimize risk to the communities we live in.

COOPER: Yes.

KAYYEM: And as that teacher said earlier on your show, her government has failed her.

COOPER: I want to thank everybody on the panel. We're going to talk to you a little bit later. It's just about the top of the hour, 9:00 p.m. here on the East Coast of the United States, 9:00 p.m. in Florida. Thanks for joining us.

[20:59:58] The breaking news tonight isn't new or novel unfortunately. It's a senseless tragedy we have seen time and time and time again. Another deadly school shooting in another American town, another high school, another community shaken to its core by a shooter with a semi- automatic weapon.